Acne vulgaris is a chronic skin condition characterized by areas of blackheads, whiteheads, pimples, greasy skin, and possibly scarring. The resulting appearance may lead to anxiety, reduced self-esteem, and depression. Genetics is estimated to cause of 80% of cases. The role of diet as a cause is unclear, and neither cleanliness nor sunlight appear to be involved. Acne mostly affects skin with a greater number of oil glands; including the face, upper part of the chest, and back. During puberty in both sexes, acne is often brought on by an increase in androgens such as testosterone. Many treatment options are available to improve the appearance of acne including lifestyle changes, procedures, and medications.
Acne occurs most commonly during adolescence, affecting an estimated 80-90% of teenagers in the Western world. Lower rates are reported in some rural societies. In 2010, acne was estimated to affect 650 million people globally making it the 8th most common disease worldwide. People may also be affected before and after puberty. Though it becomes less common in adulthood than in adolescence, nearly half of people in their twenties and thirties continue to have acne. About 4% continue to have difficulties into their forties. There are recent reports of emergence of antibiotic resistant strains of acne-causing bacteria.
Other factors affect the skin as well. For example, aging can cause changes to skin appearance and texture such as wrinkles and sagging. These changes can be related to a number of factors, including the environment, a person's genetic makeup or age, and behaviors such as sun exposure or smoking. After age 30, the amounts of collagen, elastin, and hyaluronic acid in and around the skin decrease by about 1-2% per year, and combined with sun damage the loss of these essential components can be greater than 3% per year. The natural, electrical nature of the skin is slowly diminished over time.